Common Surgical Knot Types

Surgical Knot Types

Surgical knots are a way of securely tying sutures over a specific tissue or while ligating blood vessels. Various surgical knot types and techniques are used in surgical practice and they form an important aspect of the basic surgical skillset for a surgeon.

History

In the first century of our common era, the Greek physician Heraklas wrote a brief essay on how to tie 16 surgical knots and nooses for surgical and orthopedic purposes. It was found that seven of Heraklas’ 16 knots and nooses were still applied surgically of late and that four of these have even been recently rediscovered for such applications.

Sutures are best made of soft thread, not too hard twisted that it may sit easier on the tissue, nor are too few nor too many of either of them to be put in.   Aurelius Cornelius Celsus, 25BC–AD50

In 1000bc, Indian surgeons were using horsehair, cotton, and leather sutures on the other hand, in Roman times, linen and silk and metal clips, called fibulae. At the end of the nineteenth century, the textile industry provided major advancement, and both silk and catgut became popular as Suture Materials.

Lister said that catgut soaked in chromic acid (a form of tanning) prevented early dissolution in body fluids and tissue, while Moynihan felt that chromic catgut was ideal as it could be sterilized, was non-irritant to tissues, kept its strength until its work was done and then disappeared.

However, catgut is no longer used as it causes an inflammatory cellular reaction with the release of protease and may carry the risk of prion transmission if of bovine origin.

Knot Security

Knot security is defined by the quality of the surgical knot, the technique used, the type of suture used, the body tissue, the moisture content of the wound, and whether the infection is present. The smaller the knot, the less tissue reaction, resulting in a more minimal scar.

The knot consists of the loop, knot, and ears. Knots may be hand tied or tied using instruments, but should not be over-tightened to avoid discomfort to the patient and to make the sutures easier to remove.

Absorbable sutures may be cut fairly short, leaving a length of 2–3 mm. Minimal absorbable sutures should be left internally to reduce any tissue reactions that may occur. Non-absorbable sutures should be left longer (around 10 mm) as they will require removal once the wound has healed, usually in 10–14 days.

Types of Surgical Knots

1. Square Knot / Reef Knot
2. Granny’s Knot / Slip Knot
3. Surgeon’s Knot
4. One-Handed Reef / Square Knot 
5. Two-Handed Reef / Square Knot
6. Tarun Technique
7. Buried Knot
8. Aberdeen’s Knot / Cobbler’s Knot

1. Square Knot / Reef Knot

Technique

This is the most common surgical knot technique.

Hold the Short End between the thumb and ring finger with the index finger and middle finger straight and keep the right hand in the supine position. Hold the Long End between the thumb and ring finger with the index finger and middle finger straight and keep the left hand in the supine position. Make sure to keep the short end above and the long end below for this technique.

Pull the Long End for tension and bring the short end onto the long end with the right hand’s index finger and middle finger and make ‘Figure Of 4’. Here holding the suture junction with the left hand is crucial.

Cross the remaining suture of the short end from the loop with the help of the right hand’s index and middle finger and the knot to the base of the wound with the help of the index figure or thumb. Cross the long end away from you and tighten up the first throw.

Hold the short end with your right hand’s index finger and thumb with sutures lying beneath your pronated right hand’s remaining three fingers and rotate your right hand from inside out at 180 degrees.

Bring the long end towards you and put it on your right hand’s remaining three fingers next to the short end and make a ‘V’ and hold the suture junction towards you with your left hand. Making ‘V’ is critical because you can hold the suture toward you and space between sutures away from you will give you room for making a loop.

Now pull the long end with your Right hand’s middle finger, hold your short end between your middle and ring finger, and take the short end from the loop.

Now hold both the ends and cross the short end away from you and tighten up the second throw. Voila here is your REEF knot.

2. Granny’s Knot / Slip Knot

Technique

Hold the Short End between the thumb and ring finger with the index finger and middle finger straight and keep the right hand in the supine position. Hold the Long End between the thumb and ring finger with the index finger and middle finger straight and keep the left hand in a supine position. Make sure to keep the short end above and the long end below for this technique.

Pull the Long End for tension and bring the short end onto the long end with the right hand’s index finger and middle finger and make ‘Figure Of 4’. Here holding the suture junction with the left hand is crucial.

Cross the remaining suture of the short end from the loop with the help of the right hand’s index and middle finger and the knot to the base of the wound with the help of the index figure or thumb. Cross the long end away from you and tighten up the first throw.

Hold the short end with your right hand’s index finger and thumb with sutures lying beneath your pronated right hand’s remaining three fingers and rotate your right hand from inside out at 180 degrees.

Bring the long end towards you and put it on your right hand’s remaining three fingers next to the short end and make a ‘V’ and hold the suture junction towards you with your left hand.

Making ‘V’ is important because you can hold the suture toward you and space between sutures away from you will give you room for making a loop.

Again, hold the long end with the right hand’s index finger and middle finger and the short end with the left hand’s index and middle finger.

Keep the short end below the long end

Cross the suture of the short end into the loop from beneath with the help of the right hand’s index and middle finger and cross the long end with the help of the left hand’s middle and index finger and tighten up the second throw. Here’s your granny knot.

3. Surgeon’s Knot

Start with the first stage of a square knot, and once enough throws have been completed, finish with the final stage of a square knot.

Technique

Hold the Short End between the thumb and ring finger with the index finger and middle finger straight and keep the right hand in the supine position. Hold the Long End between the thumb and ring finger with the index finger and middle finger straight and keep the left hand in the supine position. Make sure to keep the short end above and long end below for this technique.

Pull the Long End for tension and bring the short end onto the long end with the right hand’s index finger and middle finger and make ‘Figure Of 4’. Here holding the suture junction with the left hand is crucial.

Cross the remaining suture of the short end from the loop TWICE with the help of the right hand’s index and middle finger and the knot to the base of the wound with the help of the index figure or thumb. Cross the long end away from you and tighten up the first 2 throws.

Hold the short end with your right hand’s index finger and thumb with sutures lying beneath your pronated right hand’s remaining three fingers and rotate your right hand from inside out at 180 degrees.

Bring the long end towards you and put it on your right hand’s remaining three fingers next to the short end and make a ‘V’ and hold the suture junction towards you with your left hand. Making ‘V’ is critical because you can hold the suture toward you and space between sutures away from you will give you room for making a loop.

Now pull the long end with your Right hand’s middle finger, hold your short end between your middle and ring finger, and take the short end from the loop.

Now hold both the ends and cross the short end away from you and tighten up the second throw. Voila here is your Surgeon’s knot.

 4. One-Handed Reef / Square Knot

Technique

Hold long end above and short end below.

Hold the short end with your right hand’s index finger and thumb with sutures lying beneath your pronated right hand’s remaining three fingers and rotate your right hand from inside out at 180 degrees. Bring the long end towards you and put it on your right hand’s remaining three fingers next to the short end and make a ‘V’ and hold the suture junction towards you with your left hand.

Making ‘V’ is important because you can hold the suture toward you and space between sutures away from you will give you room for making a loop. Now pull the long end with your Right hand’s middle finger, hold your short end between your middle and ring finger, and take the short end from the loop.

Now hold both the ends and cross the short end away from you and tighten up the first throw

Hold Short End and wind it around the right hand’s index finger from outside to inside and put the long end winding inside to outside over the right hand’s index finger next to the short end.

Now take the free short end from the loop with the help of the left index finger. Move the knot to the base with the help of the left index finger and tighten up the knot.

5. Two-Handed Reef / Square Knot

Technique

Hold Long End with left Hand’s index finger suture winding from outside to inside and keep it tight and steady with rest fingers. Keep the long end above and the short end below.

Hold Short End and wind it around Left Hand’s index finger from inside to outside where the long end is kept and hold the loop between the left hand’s index finger and thumb.

Move the pinched index finger and thumb to the opposite side of the loop, grab the free short end suture and move back to from the loop. Hold the free short end with your right hand and cross it away from you while tightening the throw from your index finger or thumb.

Hold the long end with the right hand and slid the right thumb from outside of the stretched suture and hold the suture over your thumb’s dorsal surface. Put the short end with the right index finger and thumb over the left thumb next to the long end and pinch the index finger and thumb to hold both ends in the loop.

Move the Left-hand index finger and thumb pinch from outside to inside and grab the free short end, move it back outside the loop. Hold the short end with the right hand, move the throw with your index finger towards the base and tighten up the knot.

6. Tarun Technique

Technique

Hold the long end above and the short end below.

Hold the short end with your right hand’s index finger and thumb with sutures lying beneath your pronated right hand’s remaining three fingers and rotate your right hand from inside out at 180 degrees.

Bring the long end towards you and put it on your right hand’s remaining three fingers next to the short end. Now pull the long end with your Right hand’s middle finger on the top and pull the short end with the Left index figure at the same time.

Now pull both strands short end away and the long end towards you and tighten up the 2 throws.

7. Buried Knot

Used at the beginning of a row of intradermal sutures, a bite is taken at the end of the wound at each side through the dermis, before being secured with a Surgeon’s knot.

The knot remains within the dermal layers.

8. Aberdeen Knot / Cobbler’s Knot

Technique

At the finishing end of the subcuticular suturing take the bite with a needle from the opposite side horizontally to the skin and take out the needle part from the finishing end.

Make a loop between the last bite and make sure the loop is not twisted. Hold the loop between the right index finger and thumb.

Now hold the suture end with the needle tight and pull that suture end with the help of the middle finger. Now leave the suture from the right index finger and thumb and pull the free suture with the right ring finger at the same time and make another loop. Do not leave the suture on the left hand.

Repeat these steps and make a minimum of 6 throws but ideally, 10 throws are preferable.

At the end pull through the needle-ended suture from the loop and tighten it up.

Now take a bite from the needle from inside and get the needle out from the skin so that the whole 6-10 throw burry inside and become upside down.

Cut the remaining suture just from the skin and here is your Aberdeen knot.

Newer Wound Closure Techniques

1. Dermabond

Dermabond Advance (Ethicon) is a new type of tissue adhesive, which studies have shown to increase the strength of a skin wound closure by 75% more than sutures alone. It is available in a pen-style applicator for ease of use and is used for wounds up to 15 cm in length.

It is more flexible than other tissue adhesives currently available, and spreads tension along the wound, preventing gaping of the edges which creates a microbial barrier and inhibits Gram-positive (MRSA and MRSE) and Gram-negative (Escherichia coli) bacteria.

Bhende et al showed that there is protection against 99% of organisms responsible for surgical site infections during the first 72 hours post application.

2. Dermabond Prineo

This is available as a kit, which contains Dermabond adhesive and polyester mesh tape, to be used for skin closure in conjunction with one another (applying the adhesive to the tape).

It may be used to replace subcuticular sutures with a strength similar to that of 2 metric polyglecaprone 25 or to provide further strength to a wound in an area of high tension.

It has the same antibacterial properties as Dermabond alone, but may be used for much larger wounds when combined with the polyester mesh. Once the wound has healed fully, the mesh is removed easily from the patient.

3. Stratafix

Stratafix (Ethicon) is a suture material with inbuilt spiral barbs which retract when pulled through the tissue but re-engage and anchor once the suture is in place, avoiding the need for knots (and thus reducing inflammatory reaction to a large amount of suture material).

It has a swaged-on needle (with a choice of different needle types) and is available in both absorbable (short-term and long-term) and non-absorbable materials. The unilateral version has a fixation loop at one end, for threading the needle through to secure the material, without the need for a knot.

This is used for suturing from one end of a wound to the other and is suitable for organ closure. The bilateral design has anchors which change direction halfway through the material; this allows the surgeon to close circumferentially or close multiple layers with one length of material. It may be used for complex, curved, or irregular wounds, such as abdominoplasty or urethral anastomosis.